The present invention relates to a cooling element for use in a metallurgical furnace, particularly in a blast furnace.
The invention also relates to a method of making a cooling element of the type outlined above.
It is already known to install cooling elements of various different types in the walls of metallurgical furnaces, such as blast furnaces, in order to protect these walls against damage resulting from the high temperatures--and temperature fluctuations--occurring in operation of such furnaces. In recent years a type of cooling element has become popular, particularly for use in blast furnaces, which is known as a "plate cooler" or "stave cooler". This type of cooling element is composed of a cast-iron body in which steel tubes are embedded, and cooling medium--usually water, steam or a watersteam mixture--is circulated through these tubes. The surface of the cooling element which faces inwardly towards the furnace chamber is provided with recesses in which refractory materials are installed, for example like casting or bonding. Constructions of this type are disclosed in German Gebrauchsmuster No. 7,331,936 and in German Pat. No. 1,925,478.
This type of cooling element is basically quite satisfactory. However, the actual body of the cooling element heretofore has always been made of cast iron and more specifically of grey cast iron with differing graphite structure. This is disclosed, for example, in German Allowed Application AS No. 2,719,165.
The use of grey cast iron, however, represents a problem because the working temperature in such metallurgical furnaces is usually close to the melting point of the grey cast iron. Accordingly, it is often found--when such cooling elements are removed from the furnace--that the body of grey cast iron is partly melted. In addition to this, it is well known that even at temperatures as low as about 100.degree. C. below the melting point of such materials as grey cast iron, the technological characteristics of these materials are very poor. When such cooling elements of grey cast iron are used in metallurgical furnaces, and particularly in blast furnaces, it has accordingly been observed again and again that they exhibit signs of destruction at their side which faces inwardly toward the chamber of the furnace.